1. Field of the Invention
The present invention relates to a toolholder, and more specifically to a toolholder for use in precisely shaping the screw-engaging portion of a screwdriver or the like in a hollow-ground configuration with a grinder.
2. Description of the Prior Art
It is well known that the most advantageous shape for a screwdriver blade adapted to engage a screwhead having a single transverse slot is a shape in which opposite sides of the blade are "hollow ground"; that is, where these sides are cylindrically concave. However, screwdrivers having such a shape are relatively expensive due to the difficulties in accurately producing such a shape. The cylindrical periphery of the grinding wheel of a conventional grinder is, of course, adapted to produce a hollow-ground shape when the side of the blade is applied to the wheel. However, despite the presence of a tool rest adjacent to the wheel in many grinders, extreme care is required in manually guiding a screwdriver to produce an accurately and symmetrically hollow-ground blade of a relatively large screwdriver, and it is almost impossible with manual guidance to form an effective hollow-ground blade on a small screwdriver.
It has been recognized, therefore, to be highly advantageous to provide a relatively inexpensive toolholder which guides a screwdriver for grinding by a bench grinder or the like so as to form both sides of the blade of the screwdriver in a substantially identical hollow-ground configuration.